Author Topic: Raptor Upper Stage consolidated thread  (Read 59001 times)

Offline whitelancer64

Re: Raptor Upper Stage consolidated thread
« Reply #40 on: 05/04/2017 08:49 PM »
ITS cant use the falcon pads anyway, so there's no reason to shut down the falcon pads to add methlox.

The current plan for ITS is launching from 39A, which just happens to be a Falcon pad. At least acknowledge the clearly stated plan before speculating the complete opposite.

That's a concept. It can't be "the plan" because LC-39A can't handle the thrust a BFR would produce. 39A would have to be stripped down, dug out, and completely rebuilt to fly the BFR.

It would be cheaper and easier to build a new pad.
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Offline GreenShrike

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Re: Raptor Upper Stage consolidated thread
« Reply #41 on: 05/04/2017 08:51 PM »
If you take a few days to understand the business side of things, you'll see that this whole raptor upper stage endeavour could make a lot of sense technically, but makes ZERO sense when you consider $$$.

So... when you took your "few days to understand the business side of things", how did SpaceX's 10K+ satellite constellation factor in?

Because it's certainly a factor in Elon's and SpaceX's thinking...


"$$$" is what it's going to take to build the constellation, and that constellation is what's going to pay for Mars.


Elon Musk has said several times, that he doesn't care too much about profit, but that if his companies don't at least nearly break even, he can't justify them to investors and the whole effort become a house of cards.

Remember Musk has two degrees, Physics and Economics. He seems to use both skills very wisely.

Both degrees involve lots of math, so basic math should be a snap for him. Saving even relatively small amounts of money per launch (like $10M for a Merlin upper stage) grows very large very quickly when multiplied by the few hundred launches needed for the constellation.

Delaying the constellation until ITS is flying is putting the cart before the horse -- both will take billions to build, but the former will thereafter generate many more billions, while the latter will quickly suck up every dollar SpaceX can earn in its quest for Mars.

The Falcon series is what they have now, so *that* is what's going to orbit and build out the initial constellation, not ITS.

So the question becomes, how do you use the Falcon family the most economically to launch the constellation? You fly fully reusable and make certain that the reuse penalty doesn't balloon the number of flights needed too badly.

A Raptor upper stage fits the bill.

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Online envy887

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Re: Raptor Upper Stage consolidated thread
« Reply #42 on: 05/04/2017 09:10 PM »
ITS cant use the falcon pads anyway, so there's no reason to shut down the falcon pads to add methlox.

The current plan for ITS is launching from 39A, which just happens to be a Falcon pad. At least acknowledge the clearly stated plan before speculating the complete opposite.

That's a concept. It can't be "the plan" because LC-39A can't handle the thrust a BFR would produce. 39A would have to be stripped down, dug out, and completely rebuilt to fly the BFR.

It would be cheaper and easier to build a new pad.

I've seen this repeated many times, but never with any kind of actual data to support it. Surely that data or a way to calculate it exists somewhere. Can you provide a reference?

Offline Negan

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Re: Raptor Upper Stage consolidated thread
« Reply #43 on: 05/04/2017 09:36 PM »
ITS cant use the falcon pads anyway, so there's no reason to shut down the falcon pads to add methlox.

The current plan for ITS is launching from 39A, which just happens to be a Falcon pad. At least acknowledge the clearly stated plan before speculating the complete opposite.

That's a concept. It can't be "the plan" because LC-39A can't handle the thrust a BFR would produce. 39A would have to be stripped down, dug out, and completely rebuilt to fly the BFR.

It would be cheaper and easier to build a new pad.

I've seen this repeated many times, but never with any kind of actual data to support it. Surely that data or a way to calculate it exists somewhere. Can you provide a reference?

Doesn't exactly say either way, but here's an interesting quote from an NSF article:

"The rocket is shown to be launching from SpaceXís 39A launch site, which was in doubt based on its thrust margins. However, the rocket is close to the limitations of the padís 28 million pound parameter and is likely to be provided with a level of pad engineering mitigation to allow ITS to launch from this site."

https://www.nasaspaceflight.com/2016/09/spacex-reveals-mars-game-changer-colonization-plan/

Offline mme

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Re: Raptor Upper Stage consolidated thread
« Reply #44 on: 05/04/2017 09:59 PM »
...
I've seen this repeated many times, but never with any kind of actual data to support it. Surely that data or a way to calculate it exists somewhere. Can you provide a reference?

Doesn't exactly say either way, but here's an interesting quote from an NSF article:

"The rocket is shown to be launching from SpaceXís 39A launch site, which was in doubt based on its thrust margins. However, the rocket is close to the limitations of the padís 28 million pound parameter and is likely to be provided with a level of pad engineering mitigation to allow ITS to launch from this site."

https://www.nasaspaceflight.com/2016/09/spacex-reveals-mars-game-changer-colonization-plan/
I think they used Pad 39A in the video because it's iconic. My issue with using 39A is simply why would they take their FH and crew pad out of service to repurpose it?  Why not just build a new pad?  Otherwise they need to upgrade LC40 for FH, add a crew access tower and arm.  It makes no sense to me.
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Online rakaydos

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Re: Raptor Upper Stage consolidated thread
« Reply #45 on: 05/04/2017 10:10 PM »
It does provide some benifit, before ITS comes online. But once ITS comes online it's entirely obsolite, which puts a cap on how much it can earn for SpaceX over what the Mvac stage can. And it's pretty clear that how much it can earn is less than how much it would cost to develop and build that stage, rebuild a launch site for mixed propellants (displacing normal paying flights, which counts as a cost), and other expences of such a program.

How much it can earn? That's spoken like someone who hasn't heard that SpaceX would very much like to orbit 10K+ satellites.

Who cares about their paying flights, when to launch 4400 LEO sats they themselves will need almost 90 Falcon Heavy launches at 50 sats per FH launch? That's three times the number of current *F9* flights and almost as many as the current number of Atlas V and Delta 4 flights combined. Double that or more if they're restricted to launching them on F9s due to lack of fairing volume (a topic for another thread).

And then there's also another 7000-odd VLEO sats, so double or triple the 90 FH or 180 F9 flights.

At this point, SpaceX's commercial *paying* flights are a somewhat rough rounding error.

A Raptor S2 doesn't need to earn SpaceX a thing when at $10M per Merlin S2, 200 or 300 launches represents a couple or three billion of capital just in Merlin S2s -- and never mind the CommX payloads. It's possible SpaceX could save a good portion of that by developing a fully reusable upper stage. A billion saved is a billion earned -- isn't that how the saying goes?

And a Raptor stage won't eat performance margins for lunch like the relatively low ISP Merlin upper stage will -- a 20-30% performance penalty to the current S2 would, at flight rates of 200-300 launches, mean 40 on the low end and 90 on the high end more launches.  Even assuming a heavily discounted $30M per FH launch, 40 launches is again over $1 billion in additional costs. At a discounted $20M per F9, 90 launches is almost $2B.

The problem is that the "things it does that falcon cant" isnt big enough to cover even "Doesnt cost that much," especially since infrastructure changes (fuel lines on the erector, ect) actually would -reduce- the number of paying flights compared to a kerlox-only falcon family.

Unfortunately, "things Falcon can't" currently include launching 10K+ sats in as economical a manner as SpaceX likely needs if Elon wants to maintain control of the company.

Compared to current flight rates, a few hundred million to design and build a Raptor upper stage (hopefully with integrated sat dispenser, which, indeed, may look like a mini-ITS) and a couple hundred more to modify the GSE is blinking expensive.

Compared to what SpaceX plans, however, it's practically peanuts.


You need to keep in mind that, if you're trying to suss out what SpaceX is going to do, SpaceX will act based on the requirements of their own dreams and schemes -- which most certainly include the CommX constellation.

And those plans present SpaceX with a stark choice: a fully reusable Raptor upper stage, a reusable Merlin upper stage that adds 40 or 60 or 80 launches to a manifest that already strains credulity, or an expendable Merlin that results in $2-3 billion of SpaceX cash burned up on re-entry.

If after all's said and done, it costs SpaceX $1 billion to field a Raptor upper stage, well, even to a billionaire like Musk saving another billion in costs isn't chump change.
SpaceX only needs to put up 800 or so to start earning money- not the full multi billion per year, certiantly, but enough to make launching CommX self sustaining. They dont need FalconRaptor to do that, and need to launch into an absurd number of different inclined orbits anyway, so extra capability doesnt help their goals. FalconMvac is mature, they dont need to fund designing an entire new rocket just to launch CommX, they can just start sending up sats when they have them built. Which gets the multibillion income stream going faster than if they waited for FalconRaptor.

Online abaddon

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Re: Raptor Upper Stage consolidated thread
« Reply #46 on: 05/04/2017 10:24 PM »
I think they used Pad 39A in the video because it's iconic. My issue with using 39A is simply why would they take their FH and crew pad out of service to repurpose it?  Why not just build a new pad?  Otherwise they need to upgrade LC40 for FH, add a crew access tower and arm.  It makes no sense to me.
If 39A is ITS capable (or would be with some not huge upgrades) it would likely be much cheaper to use it for ITS and retrofit LC40 for crew than build a new ITS capable pad from scratch.  Just look at 39A in comparison with the other SpaceX pads.  It is tremendously overbuilt for Falcon 9.  It was built that way to handle really big rockets.  Something that could handle ITS thrust levels would need to be much bigger and more robust (and more expensive) than any other SpaceX pad is now, by far.  Then there's also distance/overpressure concerns, other sites might not allow for as big a rocket as 39A does due to those concerns as well.
« Last Edit: 05/04/2017 10:26 PM by abaddon »

Offline rsdavis9

Re: Raptor Upper Stage consolidated thread
« Reply #47 on: 05/04/2017 10:37 PM »
have ZERO problems raising capital for either SpaceX or Tesla.

Capital for things investors hope to profit from. Like the Internet constellation.

If you have evidence of SpaceX receiving funding from philanthropic billionaires, I'd really like to hear about it.

didnt google invest 1b in spacex?
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Offline Negan

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Re: Raptor Upper Stage consolidated thread
« Reply #48 on: 05/04/2017 10:40 PM »
I think they used Pad 39A in the video because it's iconic. My issue with using 39A is simply why would they take their FH and crew pad out of service to repurpose it?  Why not just build a new pad?  Otherwise they need to upgrade LC40 for FH, add a crew access tower and arm.  It makes no sense to me.

The revenue lost could be less than the cost of building a new pad.

Online envy887

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Re: Raptor Upper Stage consolidated thread
« Reply #49 on: 05/04/2017 11:54 PM »
I think they used Pad 39A in the video because it's iconic. My issue with using 39A is simply why would they take their FH and crew pad out of service to repurpose it?  Why not just build a new pad?  Otherwise they need to upgrade LC40 for FH, add a crew access tower and arm.  It makes no sense to me.

The revenue lost could be less than the cost of building a new pad.

They have two other East Cost pads coming online soon. The only unique thing about 39A is crew access.

Offline corneliussulla

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Re: Raptor Upper Stage consolidated thread
« Reply #50 on: 05/05/2017 06:58 AM »
I think raptor upper stage is off the table....until there is money in producing such a thing....NASA just sent out a RFI for delivering material to the moons surface, maybe a raptor equipped upper stage of a falcon heavy would be a good solution for this requirement.

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Re: Raptor Upper Stage consolidated thread
« Reply #51 on: 05/05/2017 07:09 AM »
I think raptor upper stage is off the table....until there is money in producing such a thing....

With the upcoming satellite constellation there is a lot of money in a reusable upper stage that does not reduce present capability of the Falcon family.

A Raptor upper stage is also a great risk reduction strategy for building ITS.

If they can also serve NASA needs to the moon that is great. It would require a engine powered landing capability with landing legs. I was never comfortable with parachutes and bouncy castles or helicopters.

Sending them to Mars, I wonder if a much smaller stage than ITS can handle boiloff efficiently.

Offline Semmel

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Re: Raptor Upper Stage consolidated thread
« Reply #52 on: 05/05/2017 12:03 PM »
I agree with Jim, it probably does not make sense to develop a raptor upper stage economically if it is expendable. So I agree with the opposite argument as well, if a RUS is done so that it can be re-used, it can make economic sense. Despite all the trouble in ground systems.

In terms of performance, a RUS is clearly superior. But again, Jims argument holds that F9 does not need more performance. It can serve the current market just fine as it is. Also, I dont think F9 can deliver the payload advertised on the web page. Not for lack of dV, but for structural and horizontal integration design reasons.

For the CommX constellation, it might make sense to consider some redesigns. Its a large enough number of flights to do changes to the architecture.
Lets start with F9. It currently costs, when reused and with reusable fairings in the order of $30M. It is limited to 10.5 mT in a fairing because the payload, after integration is suspended on the fairing. Since FH supposedly uses the same integration strategy, its also limited to 10.5 mT payload in a fairing. SpaceX develops FH not to lift heavier payloads, but to lift moderately heavy payloads, up to 10 mT to a high energy orbit. It can do that just fine for the current market and there is no economical incentive to change that. Since F9 is most likely volume limited for the constellation, it would make sense to develop a version of the second stage that is reusable at the cost of payload mass. Since F9 is not mass limited anyway, no performance in terms of number of satellites launched is lost. This might drop the cost per launch from $30M to $20M for some investment into a reusable version of the current upper stage, say $100M. No alteration of ground support is necessary.

So, what can be done for the constellation? First off, given the weight of the sats (<400kg each), F9 s probably volume limited, not mass limited. So in order to increase the number of sats per launch, a bigger fairing is necessary. But then, the structural loads during integration will still limit the payload mass to 10.5 mT. Given that, a redesign of the second stage and payload adapter and fairings and integration strategy is needed, so vertical integration. This limits the launch to be done from 39A but, which I understand is not SpaceXes desire. But it could be done to send large batches of sats on a FH. As a result, the number of sats to orbit can already be increased without a RUS but requires some redesign. We dont know if that might already be part of Block 5. Lets guesstimate (you can argue the numbers of course) that the redesign would cost in the order of $80M and that a FH launch including the above would cost $60M to launch.

A RUS, in order to provide its most advantage, would require a larger diameter. This is already a big minus in terms of logistics, factory, tooling and re-certification of F9. A completely new payload adapter, fairing design and ground support are also necessary. This would cost up front, say $500M, due to factory, tooling, infrastructure and ground support changes on all launch pads as well as design and engineering work. This kind of investment would only make sense if it was re-usable. If it is, it might be possible to conduct a launch for $20M, eliminating $10M for the reusable second stage from the unchanged F9 with reusable first stage and fairings. This kind of rocket might be able to get in the order of 15mT for F9 and maybe 70mT in terms of FH into a valid constellation orbit.

To summarize:
Option 1: no change, launch cost $30M a piece. No additional investment. Volume limited number of sats, say 20 sats.
Option 2: re-usable version of the current upper stage, investment ~$100M, $20M per launch. Volume limited number of sats, say 20 sats.
Option 3: Redesign to max out the mass to orbit for the constellation. Investment ~$80M, only beneficial at 39A, mass limit of sats to orbit, say 125 sats per $60M launch of FH.
Option 4: Raptor based upper stage, investment $500M, mass limited number of sats. 37 or F9 of $20M a piece and 175 for FH with $50M a launch.

That are the tradeoffs to make for the constellation. It seems to me, that a RUS is far more expensive up front than a reusable second stage version of the current one. So as Musk hinted in a tweet to look into reusing the upper stage. And it makes sense if you assume that the constellation is really volume limited and not mass limited. A Raptor upper stage, being viable if it flies often enough and allows for mass limited launches of the constellation. But it comes with a much much higher risk if re-usability doesnt work out as advertised. So I think its not a good option, given the tradeoff above. Also, if BFR/ITS comes online in 10 years or so. The second generation of the constellation might just be launched on BFR/ITS, eliminating the need for the raptor upper stage all together. In THAT light, RUS is taking highly needed funds from ITS, delaying ITS and is a lot more risky than trying to develop a reusable upper stage based on the current design. Gwynne will make sure that Elon doesn't go off on a tangent with RUS. SpaceX will have the same trade offs I outlined above, more refined of course. But even if my numbers are wrong by a factor of 2, RUS still doesnt make economic sense. The only benefit would be to give Raptor some flight history. But I think thats not enough of an incentive.
« Last Edit: 05/05/2017 12:10 PM by Semmel »

Offline jpo234

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Re: Raptor Upper Stage consolidated thread
« Reply #53 on: 05/05/2017 12:18 PM »
http://aviationweek.com/space/us-air-force-lines-space-launch-vehicle-investments talks about possible updates for FH helped by the Air Force.
You want to be inspired by things. You want to wake up in the morning and think the future is going to be great. That's what being a spacefaring civilization is all about. It's about believing in the future and believing the future will be better than the past. And I can't think of anything more exciting than being out there among the stars.

Offline hkultala

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Re: Raptor Upper Stage consolidated thread
« Reply #54 on: 05/05/2017 12:48 PM »
I think raptor upper stage is off the table....until there is money in producing such a thing....

With the upcoming satellite constellation there is a lot of money in a reusable upper stage that does not reduce present capability of the Falcon family.

LEO communications satellites are very light, and the payload capasity is often not the bottleneck; the bottleneck might be different destination orbits required and/or fairing volume.

Then can recover merlin 1d-based second stage while still launching MANY satellites per launch, and methane-based upper stage might just make price/satellite more expensive due more complex launch site needed.

For big GTO/BEO payloads, methane-based second stage would help.

Offline spacenut

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Re: Raptor Upper Stage consolidated thread
« Reply #55 on: 05/05/2017 01:48 PM »
Negan, Pad 39A's thrust limit is 12 million lbs.  (Originally designed for a Nova Class rocket, with 8 F-1 engines).  ITS proposed 28 million will not launch from 39A.  It will require a new launch pad. 

This is why all the talk of a Raptor upper stage.  With FH coming on line, and a proposed reusable upper stage late this year, there is speculation of a Raptor based upper stage, giving FH about 10 tons extra payload to LEO.  This would put it in the lower range of the SLS which was to be 70-130 tons to LEO with upgrades. 

A Raptor upper stage might be a little too large for F9, but not for FH.  If it is a Raptor upper stage, it would need to be reusable, and test various components for future ITS. 

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Re: Raptor Upper Stage consolidated thread
« Reply #56 on: 05/05/2017 02:42 PM »
I think raptor upper stage is off the table....until there is money in producing such a thing....

With the upcoming satellite constellation there is a lot of money in a reusable upper stage that does not reduce present capability of the Falcon family.

LEO communications satellites are very light, and the payload capasity is often not the bottleneck; the bottleneck might be different destination orbits required and/or fairing volume.

Then can recover merlin 1d-based second stage while still launching MANY satellites per launch, and methane-based upper stage might just make price/satellite more expensive due more complex launch site needed.

For big GTO/BEO payloads, methane-based second stage would help.

The constellation is LEO but quite high. If they circularize to 1000km payload capacity can quickly become a bottleneck. They can decide to let the satellites do circularization, that would reduce lift requirements.

When they redesign the upper stage for reusability they have a strong incentive to do it with methalox. Not only so they can fly all payloads, including GTO, but also because they learn a huge amount for ITS technology with limited financial risk.

IMO it is all or nothing. Since they seem to have decided for something, I believe it will be all.

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Re: Raptor Upper Stage consolidated thread
« Reply #57 on: 05/05/2017 02:45 PM »
@Semmel

I like your summary. But about vertical integration. If they need it for lifting higher mass I am quite confident they can do it at LC-40 with something as simple as a crane. I doubt their constellation satellites will have requirements to be accessed after integration into the fairing.

Offline RonM

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Re: Raptor Upper Stage consolidated thread
« Reply #58 on: 05/05/2017 02:46 PM »
Negan, Pad 39A's thrust limit is 12 million lbs.  (Originally designed for a Nova Class rocket, with 8 F-1 engines).  ITS proposed 28 million will not launch from 39A.  It will require a new launch pad. 

This is why all the talk of a Raptor upper stage.  With FH coming on line, and a proposed reusable upper stage late this year, there is speculation of a Raptor based upper stage, giving FH about 10 tons extra payload to LEO.  This would put it in the lower range of the SLS which was to be 70-130 tons to LEO with upgrades. 

A Raptor upper stage might be a little too large for F9, but not for FH.  If it is a Raptor upper stage, it would need to be reusable, and test various components for future ITS.

I think a smaller first generation ITS with a thrust under 12 million lbs would make more sense than a RUS for FH. A Nova sized ITS would be good for satellite deployment and Mars exploration.

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Re: Raptor Upper Stage consolidated thread
« Reply #59 on: 05/05/2017 03:21 PM »
Negan, Pad 39A's thrust limit is 12 million lbs.  (Originally designed for a Nova Class rocket, with 8 F-1 engines).  ITS proposed 28 million will not launch from 39A.  It will require a new launch pad. 

This is why all the talk of a Raptor upper stage.  With FH coming on line, and a proposed reusable upper stage late this year, there is speculation of a Raptor based upper stage, giving FH about 10 tons extra payload to LEO.  This would put it in the lower range of the SLS which was to be 70-130 tons to LEO with upgrades. 

A Raptor upper stage might be a little too large for F9, but not for FH.  If it is a Raptor upper stage, it would need to be reusable, and test various components for future ITS.

What's the 12 mlbf number based on? SpaceX says they are going to launch ITS from 39A. Maybe they are, maybe they aren't.

But if you're going to argue that they CAN'T launch form 39A, you should have some analysis to back that up. "Designed for 8x F-1" just puts a minimum bound on the thrust ceiling, it doesn't automatically follow that a larger vehicle cannot launch.

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